Contemporary population ethics is dominated by views that aggregate by summing, whether of well-being or of some construct based on well-being. In contrast, average well-being is generally considered axiologically irrelevant. To many of us, however, the number of future people does not seem important, as long as it is sufficient to enable rich and varied life experiences, and as long as the population continues throughout time. It therefore seems relatively plausible to aggregate future well-being by averaging. In particular, it seems plausible to value high average well-being at any particular time, and to do so for all future times. I present a time-sensitive version of the Average View that underpins such axiological intuitions. I also address a series of issues and objections that confront such a view.

As opposed to overdemanding principles which ask individuals to sacrifice too much, there are overpermissive principles which ask individuals to sacrifice too little. Determining the extent to which one should sacrifice often comes with the need of understanding what is of moral significance. By analysing different readings of moral significance, and singling out one specific interpretation of moral significance which links moral significance to gaining or losing a considerable amount of welfare, I demonstrate that one of the well-known principles of Peter Singer, the Weaker Principle of Sacrifice, is overpermissive as it exempts deliberately cultivated morally significant lavish pursuits from the domain of sacrifice. Overpermissiveness not only renders moral principles unreasonably broad but also causes burdens to be distributed unjustifiably in a comparative sense, where some parties are assigned a moral obligation whereas others are not.

Pattern-based reasons are reasons for action deriving not from the features of our own actions, but from the features of the larger patterns of action in which we might be participating. These reasons might relate to the patterns of action that will actually be carried out, or they might relate to merely hypothetical patterns. In past work, I have argued that accepting merely hypothetical pattern-based reasons, together with a plausible account of how to weigh these reasons, can lead to disastrous consequences. However, in this article, I argue that this problem is not limited to hypothetical pattern-based reasons: it turns out that there are analogous issues for reasons deriving from actual patterns. I then suggest that we can avoid this problem by adopting a different account of the weight of pattern-based reasons.

Global warming is a very complex collective harm. While various models have been proposed to assign moral responsibility in such cases, global warming presents an additional problem. The complexity of the climate system gives rise to ineliminable indeterminacy, which makes it impossible to determine the extent to which any particular emissions contribute to this collective harm. This indeterminacy poses an obstacle to assigning moral responsibility to individuals. To overcome this obstacle, I propose adopting a supervaluationist approach. This approach has several benefits. Among other things, it supplies a framework for assigning moral responsibility that handles indeterminacy that commonly arises when dealing with complex, global collective-harm scenarios.